This invention relates to hot-melt adhesive sheets and semiconductor devices. More particularly, this invention relates to a hot-melt adhesive sheet that provides very precise bonding and exhibits a stress-relaxation capacity. It also relates to highly reliable semiconductor devices in which the semiconductor element therein is bonded to its element attachment site using this hot-melt adhesive sheet.
Hot-melt adhesivesxe2x80x94which have the capacity to bond various substrates once the adhesive has been softened by heatingxe2x80x94also find use as adhesives for bonding semiconductor elements to the corresponding element attachment sites. For example, Japanese Patent Application Laid Open (Kokai or Unexamined) Number Sho 61-201432 (201,432/1986) teaches a method in which a hot-melt adhesive is first coated on an integrated circuit-bearing silicon wafer and the semiconductor elements cut from that wafer are then bonded to their attachment sites.
However, since hot-melt adhesives employ a heat softening regimen, their use to bond a semiconductor element to its attachment site has been associated with the problem of an inability to achieve highly precise bonding due to outflow of the adhesive into the area surrounding the element and variations in the thickness of the adhesive. Moreover, hot-melt adhesives have had a poor stress-relaxation capacity under challenge by thermal shock, which has resulted in a reduced device reliability for semiconductor devices containing a semiconductor element that has been bonded to its attachment site by a hot-melt adhesive.
The present invention is directed to a semiconductor device comprising a semiconductor element; a substrate; and a hot-melt adhesive sheet bonding the semiconductor element to the substrate, wherein the hot-melt adhesive sheet comprises a spacer having the form of a sheet and a hot melt adhesive on both sides of the spacer.
The present invention is also directed to a semiconductor device comprising a semiconductor element; a substrate; and a hot-melt adhesive sheet bonding the semiconductor element to the substrate, wherein the hot-melt adhesive sheet comprises a mixture of a hot melt adhesive and a spacer, wherein the adhesive is selected from a silicone-modified epoxy resin adhesive, a silicone adhesive, and a silicone-modified polyimide adhesive, and the spacer has the form of particles.